Standards for media transport over IP

For years, Serial Digital Interface (SDI) has been the common standard for transporting uncompressed video within facilities, and allowed broadcasters to connect equipment together safe in the knowledge that they would work together.

When IP contribution emerged, standards were agreed for the transport of SDI signals over IP – most notably the SMPTE 2022 standards for transport and protection, and the JPEG and MPEG standards for compression. As a result, IP contribution networks can feature a variety of equipment from different vendors.

As IP makes in-roads into the studios, it is imperative for the industry to agree standards that will provide that same flexibility and avoid vendor lock-ins. Not only that, but since IP is set to blur the distinction between studios, campuses and remote locations, the standards that are proposed for transport within the facilities will also become the de facto standards for remote production and contribution.

The proposed standards were not developed by any one particular vendor, and are the result of bringing together the diverse experience of many specialists in the industry. This means these standards are not skewed or limited by the perspective of any single supplier.

A clear, progressive path to standards adoption

The VSF recommendations offer a progressive path to the adoption of standards in the facilities.

SMPTE 2022-6

In the first instance, the VSF recommends the use of SMPTE 2022-6, which enables SDI signals to be transported over IP using the Real-time Transport Protocol (RTP).

This standard is already widely in use in IP contribution networks, and supported by a number of vendors including Nevion, who were one of the earliest adopters and have over 20 deployments using it. As SMPTE 2022-6 can carry any SDI signals, it can be used both for multiplexed signals (eg multiple video and audio) and individual video signals. So, for example, SMPTE 2022-6 was used for video transport in the initial phases of VRT and EBU’s LiveIP project, which involved building and operating a Live TV production studio with state of the art IP-based and IT-centric hardware and software.

VSF TR-04

The TR-04 is a technical recommendation to use SMPTE 2022-6 for video with embedded audio and AES67 for separate audio streams, the latter being a standard that is already supported by many vendors. It is a first step towards transporting the essences (ie. individual signals) rather than the composite media.

VSF TR-03

The TR-03 is a technical recommendation that takes a real essence-based approach (where each signal type is transported individually but with synchronisation information). This approach is better suited for a production environment than a composite approach as, for example, it makes audio processing much easier since no de-embedding and re-embedding is required.

TR-03 encompasses a number of existing standards for mapping various essences onto RTP, the standard protocol for real-time transport over IP. For video, the standard is RFC 4175, for audio it’s AES67, and for clock synchronization it’s SMPTE 2059 which builds upon IEEE 1588 Precision Time Protocol (PTP).

RFC 4175 in particular brings video transport into the digital age, by transporting only the visible part of the video (active pixels) thereby reducing the volume of data transported.

Work is on-going, for example within the Advanced Media Workflow Association (AMWA), to look at aspects that will be key to delivering the full benefits of IP, in particular standardizing registration (making equipment known to the IP network) and discovery (making use of the capabilities offered by that equipment).

SMPTE 2110

SMPTE began work in January 2016 to develop a set of standards specifying the carriage, synchronization, and description of separate elementary essence streams over IP for the purposes of live production, based on the VSF Technical Recommendations TR-03 and TR-04. The work is being documented as SMPTE 2110.

Promoting standards

In December 2015, a number of broadcast equipment vendors, including Nevion, Imagine Communications, Grass Valley, Snell Advanced Media, and Lawo founded the Alliance for IP Media Solutions (AIMS) trade association that is pushing for the adoption, standardization and development of open standards, such as those recommended by VSF, SMPTE and the EBU.

At NAB 2016 (Las Vegas, 18-21 April 2016), many members of AIMS will be demonstrating IP interoperability on their booths using SMPTE 2022-6 and TR-04. Nevion demos will be feature equipment from AJA, Arista, Cisco, Elemental, GrassValley, Harmonic and Tektronik.

Nevion’s booth is located at SU5510. The AIMS booth can be found at SL9406.